Internal Apple power supply unit for some models of PowerMac G5. To confirm if this is the correct replacement, you need to check your original power supply to see if it is a 600W unit. You can also check the EEE code which is the penultimate 3 characters of the serial number of the power supply (not the Mac). This is the correct power supply if the EEE code is NUP, P25, Q9Z, QRN, QRP, QTS or QTT.